Designers have to ensure that the Client is aware of their obligations under CDM before they start any design work. Designers should have sufficient knowledge of the Client’s duties to be able to assess their knowledge and advise them of their role as part of early discussions about the project. When preparing or modifying a design, the Designer must take into account the general principles of prevention and any preconstruction information to eliminate (so far as is reasonably practicable) foreseeable risks over the life of the structure to the health or safety of people: 
•  carrying out, or liable to be affected by, construction work
•  maintaining or cleaning a structure
•  using a structure designed as a workplace

Where it is not possible to eliminate these risks, the Designer must (so far as is reasonably practicable):
•  take steps to reduce or, if that is not possible, control the risks through the design process
•  provide information about those risks to the Principal Designer
•  ensure appropriate information is included in the health-and-safety file

Designers must take all reasonable steps to provide sufficient information about the design, construction or maintenance of the structure. This information is required to assist the Client, other 
Designers and Contractors to comply with their duties under CDM 2015. CDM 2015 requires that information to be comprehensible and provided “as soon as is practicable”.